The weakening of a vessel wall from damage or disease can lead to vessel dilatation and the formation of an aneurysm. Left untreated, an aneurysm can grow in size and may eventually rupture.
For example, aneurysms of the aorta occur in the abdominal region, usually in the infrarenal area between the renal arteries and the aortic bifurcation. Aneurysms can also occur in the tortuous thoracic region between the aortic arch and renal arteries. The rupture of an aortic aneurysm results in massive hemorrhaging and has a high rate of mortality.
Damage or disease of a vessel such as the aorta may also result in a dissection of the vessel wall. Aortic dissections are usually caused by a connective tissue disorder and/or high blood pressure. Left untreated, an aortic dissection can rupture or critically reduce blood flow to the heart, the brain, the spinal cord, the abdominal organs and the legs.